Mobile communications networks are in the process of offering increasingly sophisticated capabilities associated with the motion and/or position location sensing of a user equipment (UE). New software applications, such as, for example, those related to personal productivity, collaborative communications, social networking, and/or data acquisition, may utilize motion and/or position sensors to provide new features and services to consumers. Moreover, some regulatory requirements of various jurisdictions may require a network operator to report the location of a UE when the UE places a call to an emergency service, such as a 911 call in the United States.
Such motion and/or position determination capabilities have conventionally been provided using digital cellular positioning techniques and/or Satellite Positioning Systems (SPS). Additionally, with the increasing proliferation of miniaturized motion sensors (e.g., simple switches, accelerometers, angle sensors, etc.), such on-board devices may be used to provide relative position, velocity, acceleration and/or orientation information.
In conventional digital cellular networks, position location capability can be provided by various time and/or phase measurement techniques. For example, in Code Division Multiple Access (CDMA) networks, one position determination approach used is Advanced Forward Link Trilateration (AFLT). Using AFLT, a UE may compute its position from phase measurements of pilot signals transmitted from a plurality of base stations. Improvements to AFLT have been realized by utilizing hybrid position location techniques, where the UE may employ an SPS receiver that can provide position information independent of the information derived from the signals transmitted by the base stations. Moreover, position accuracy can be improved by combining measurements derived from both SPS and AFLT systems using conventional techniques.
Furthermore, navigation devices often support popular and increasingly important SPS wireless technologies which may include, for example, the Global Positioning System (GPS) and/or a Global Navigation Satellite System (GNSS). Navigation devices supporting SPS may obtain navigation signals as wireless transmissions received from one or more transmitter equipped satellites that may be used to estimate geographic position and heading. Some navigation devices may additionally or alternatively obtain navigation signals as wireless transmissions received from terrestrial based transmitters to estimate geographic position and heading and/or include one or more inertial sensors (e.g., accelerometers, gyroscopes, etc.) that reside on-board the navigation device to measure an inertial state of the navigation device. Inertial measurements obtained from these inertial sensors may be used in combination with or independent of navigation signals received from satellite and/or terrestrial based transmitters to provide estimates of geographic position and heading.
Sensor-assisted navigation techniques (e.g., navigating from a previous location fix using motion sensors) provide a significant improvement in positioning performance, but at the expense of increased power consumption. Power is used in operating device sensors, acquiring and tracking GNSS signals, and processing the high data rate information from these multiple sources. Accordingly, there is a need to mitigate the net power consumption when using sensor-assisted navigation techniques.